Remember the Cant: Season 1, Episode 3

We begin with Holden's message throwing Mars under the bus for the destruction of the Canterbury being transmitted all over Ceres.

There's now major tension brewing between the Belt and Mars … tension that will lead to rioting on Ceres ...

... and Havelock being seemingly murdered by street thugs.

Elsewhere on Ceres, Miller continues his search for Julie Mao, even though Captain Haddid has told him to drop the case in light of the situation with the Canterbury.

Miller tracks down Anderson Dawes (Jared Harris), the charismatic and mysterious OPA leader on Ceres, who denies all knowledge of Julie and her being on board the Scopuli. Reminder: The Outer Planets Alliance, or OPA, is a unsanctioned political group fighting for Belter rights.

Meanwhile, the survivors of the Canterbury are being interrogated on board the Martian warship, the Donnager.

Lt. Lopez uses a series of intimidation tactics to rattle the crew, making some of them believe that Naomi might be an OPA sleeper agent who helped destroy the Cant.

As a former Martian Navyman himself, Alex is especially keen to this theory …

… a theory that seems all the more likely when a mystery ship is spotted en route to the Donnager, which Martian Captain Yao believes was sent to rescue Naomi.

Back on Earth, Chrisjen Avasarala manipulates her old friend and colleague, Franklin DeGraaf, the U.N. Ambassador to Mars, to raise alarm bells with the Martian government that prompts them to check their arms facilities. She lies to him that intel indicates the stealth ships that blew up the Canterbury came from Mars. She has Frank monitored.

When Frank's calls to Mars indicate that he was inquiring about stealth ships/stealth tech - and reports are that nothing is missing - Avasarala is convinced Mars is innocent in the Canterbury's destruction. After all, if Mars was guilty, why would they secretly check if their stealth was missing?

However, when Mars realizes Frank was tracked by Avasarala and in turn secret weapons facilities were exposed, he's banned from Mars. He cuts all ties with his former friend.  

So if Mars didn't destroy the Canterbury, who did? "Someone who's trying to start a war," says Chrisjen.